DESCRIPTION (Taken directly from the application) Mutations in the cystic fibrosis transmembrane regulator (CFTR) often result in a failure of the mutant protein to be properly processed at the level of the endoplasmic reticulum (ER). As a result the mutant protein is not delivered to the plasma membrane where it likely functions as a chloride transporter. Of the disease related mutations, the most common involves a deletion of phenylalanine at position 508 (delta F508). It is generally believed that the delta F508 mutant fails to fold properly while present at the ER, and subsequently is targeted for degradation. The folding defect manifested by the delta F508 mutant appears to be relatively subtle. Simply lowering the growth temperature of cells expressing delta F508 results in a portion of the mutant protein to be properly processed and move to the plasma membrane. These cells now exhibit forskolin dependent chloride transport. Prompted by this observation, we initiated studies designed at identifying new ways by which to elicit movement of mutant CFTR to the plasma membrane. We show that treatment of the delta F508 expressing cells with a number of different compounds, referred to as "chemical chaperones," corrects the processing defect of mutant CFTR, and results in the cells now exhibiting cAMP dependent chloride transport. Consequently further experiments aimed at understanding the rate-limiting steps governing movement of newly synthesized CFTR out of the ER, both in cells incubated in the absence and presence of chemical chaperones, are presented. In addition, using both in vivo and in vitro approaches, we will examine the possible participation of cellular components, notably different molecular chaperones, which may participate in the folding and maturation of newly synthesized CFTR. These experiments will provide for a better understanding of the mechanisms and cellular machinery's involved in the maturation of CFTR and perhaps lead to new strategies by which to successfully treat those individuals with the disease.